Funds are requested to purchase a hybrid quadrupole-time-of-flight laser mass spectrometer (QTOF) for the UCLA Pasarow Mass Spectrometry Laboratory. This is a shared facility jointly supported by the Department of Chemistry and Biochemistry (College of Letters and Sciences) and the Department of Psychiatry and Biobehavioral Sciences (School of Medicine) that is available to the entire UCLA campus research and teaching enterprise. There is no instrument of this type on the UCLA campus. Because of their sensitivity and selectivity, so-called QTOF instruments have been proven to be indispensable for the rapid and reliable identification of proteins from a variety of sources including spots excised from polyacrylamide gel electrophoretograms. This instrument will be a central feature of the UCLA proteomics initiative which is now being established. An instrument of QTOF design with all accessory components necessary for routine protein identification, is essential for the continued productivity, success and competitiveness of a growing number of campus research programs. Reflecting this diversity of use, descriptions of the research of the major users of the instrument are provided.